List games for the psone that were great but unpopular (hence the title hidden gems)
-Trap Gunner
-Klonoa: Door to Phantomile
-Einhander (maybe not this one...)
-Star Ocean: The second story (translation were bad...but this game had that certain charm)
-Strider 2 (simple old school fun)
-Omega Boost
-Alundra (this game was a b***h to beat)
-Super Puzzle Fighter II (this game is addicting)
-Bushido Blade
-Wild 9
-Jade Cocoon (slightly boring...but eh)
-Saga Frontier
-Nightmare Creatures (control sucked, game play wasn't any good, but dammit i like this game)

Soukyu Gurentai is great!

but most of the games you said arent really unpopular imo oo)

• Buttsubushi - unexpectedly great, probably the only good thing Phoenix Games ever published
• Arc the Lad 2 - excellent strategy RPG, not exactly unknown but it was released late in the console's life in a fairly expensive limited-run package
• Bishi Bashi series - great in multiplayer, and just in general
• Sanvein - a sort of arena shooter thing, but its really weird and stylish and interesting. and cheap.

Crisis Beat - The only 3D beat'em up that seems right to me, the fighting system, the stages and the bosses felt like the old games like Final Fight and such. Double the fun if playing together.

Deception 3: Dark Delusion. The story is pure lol (largely due to the QUALITY translation) but the gameplay is unique and engaging.

Eretzvaju, another game marred by QUALITY translation and voice acting but a pretty decent 3D fighter underneath.

Ghost in the Shell- Don't think this was very popular despite the anime tie-in. It's a unique 3D shooter and quite fun.

Tales of Destiny, overshadowed by the rest of the series but still an entertaining little RPG.

Umihara Kawase Shun, JP onry but one of the best platform games ever, in my opinion.

Rapid Reload. It's like Gunstar Heroes.

2nded on Sanvein. It's by Success who also did the Psyvariar shmups and Homura.

HOwz about

Kartia: card of fate

tactics game before final fantasy tactics, had a rock paper scissors approach, and actually let you play vs against a friend, or against the computer for extra stuff

Skullmonkeys- Fucking fun, and the art's amazing. Claymations!

Azure Dreams- Dungeon Explorer, Get married, stuff like that.

Raiden in Japanese- Fun, fun, fun. Anything more?

Tales of Destiny II- Hard to say. Fun, flashy, yet the battle system is the old, hard as shit crap.

>>2
The Saturn version is better. PSX version is good with the voices and extra ship, but it has slowdown.

Tomba and Klonoa are my two favorites.

Pepsiman

>>11
PEPSI FOR TV-GAME

GUNGAGE
motherfuckers.

Seconding Crisis Beat and Eretzvaju. The japanese version was awesome. Specially when you're a animu fan.

Toma Runner - If only this game was released in the west, and not that piece of crap Running Wild, the whole foot racing genre might have taken off.

My Kitchen - Played and loved by few as a demo, still the best cooking game ever released.

Muscle Ranking games - Obscure japanese TV game show made into a even more obscure japanese-onry video game. Only by completing a series of physical challenges, can you (and a friend) win the ultimate prize....a car! and maybe some money.